Bushing



.ug. 7, 1945. s.- 'rr-:RPAK ET AL BUSHING Filed Sept. 17, 1942 PatentedAug. 7, 1945 RUSHING Stephen Terpak and Lynn Wctherill, Plttsiicld,

Mass., assignors to General Electric Company, a corporation of New YorkApplication September 17, 1942, Serial No. 458,640

Claims.

Our invention relates to bushings, and to a bushing construction forsuch electrical apparatus as transformers and circuit breakers.

Bushings have been provided for accommodating electrical conductorswhich pass through an enclosing casing of electrical apparatus, such astransformers and circuit breakers. Such bushing constructions haveincluded an outer shell of suitable insulating material such asporcelain which is adapted to be supported on the cover of theapparatus. In order to seal the outer end of the bushing constructionfrom the weather, bushings have been employed with a resilientconnection between the outer end of the conductor and the top end of theouter porcelain shell, the connection also including a flexiblediaphragm which is sealed to the conductor and the porcelain.

It is, therefore, an object of our invention to provide an improvedflexible and sealed connection arrangement at an end of a bushingconstruction.

Another object of our invention is to provide an improved iiexible andadjustable connection at one end of a bushing, and an improvedrelatively `rigid connection at the opposite end of the bushingconstruction.

A further object of our invention is to provide an improved sealedbushing construction for electrical apparatus, wh'ich is simple inconstruction, economical to manufacture and reliable in operation.

Further objects and advantages of our inven tion will become apparentfrom the following description referring to the accompanying drawing,and the features of novelty which characterize our invention will bepointed out in the claims annexed to and forming a part of thisspecification.

In the drawing Fig. l is a sectional side elevation of a bushingconstruction which is provided with an embodiment of our invention; Fig.2 is a sectional side elevation of th'e upper portion of the bushingconstruction illustrated in Fig. 1; Fig. 3 is a. sectional sideelevation of the lower portion of the bushing construction illustratedin Fig. 1; and Fig. 4 is a fragmentary view of a portion of the upperpart of the bushing construction illustrated in Fig. 2 illustrating amodification of our invention.

The illustrated embodiment of our invention includes a, bushingconstruction having a shell arrangement of suitable insulating materialand a tubular conductor therein. The inner end of the conductor isrelatively rigidly attached to the adjacent inner end portion of theshell, and the outer end of the conductor is relatively adjustablyprovided between these cooperating portions. The

inner end of the metallic member has a nut `threaded thereon whichcooperates with an adjacent inner portion of the shoulder of th'e shellportion. The outer end of the shell, which is shown as an expansionchamber for dielectric liquid, is relatively resiliently and adjustablyattached to the adjacent end of the conductor through a cap memberwhich' is threaded to the end of the conductor, there being springsbetween the cap member and the adjacent end portion of tne shell. inorder to provide a substantially pressure-tight seal, a iiexiblediaphragm is provided which is sealed to the cap member and rto the endportion of th'e shell, The cap member is provided with a ilange ordepending Portion which protects the flexible diaphragm, the iiangemember terminating relatively close to an adjacent portion ci the shellend member. The amount of clearance between these portions Will give avisual indication of the relative compression of the spring member.

Referring tothe drawing, in Fig. 1 we have illustrated a bushingconstruction including a shell I0 having an upper shell portion Il and alower shell portion I2, these portions being composed of any suitableinsulating material, such as porcelain. Between these two shell portionsthere is provided a supporting or clamping ilange I3 having a portion I4which may be attached to the casing of any suitable electric apparatus,such as a transformer or a circuit breaker. Vfithin th'e shell membersthere is provided a conductor I5. In order to insulate suitably theconductor I5 we provide a number of concentric tubular members I6 of anysuitable insulating material. Further insulation and cooling may beprovided for the conductor by filling the bushing with an insulatingfluid, such as oil to the level I'I of a chamber member I8 which, asstated above, constitutes the outer end of the shell and is supported onthe shell portion II and which may provide an expansion chamber in thatportion of the housing above the level I1.

In order to relatively flexibly support the conductor I5 to theporcelain shell the upper end of the chamber I8 is provided with aninwardly extending portion I9 for supporting a plurality of resilientmembers or springs 2li. A terminal cap 2l the gasket at the lower endwill be placed 2| is provided h'aving a tubular portion 2,2 which undercompression as will the springs 2l.

is adiustably attached 'to the adjacent end of the In order to determinethe amount of compresconductor member Il in any suitable manner such asby cooperating threads 23. Thus, by rotating the cap member 2| thetubular portion 22 may be threaded on to the adjacent end of theconductor Il in varying amounts. In order to resiliently support theconductor I5 and cap member 2|, the spring members 2|! abut against anadjacent flat surface 24 of the terminal cap 2| through' any suitablearrangement such as through a tubular washer 2l.

In order to seal substantially pressure-tight the upper end of theporcelain shell or expansion chamber I8, a diaphragm 26 is providedwhich may be sealed to the terminal cap and expansion chamber in anysuitable manner. As will be seen more clearly in Fig. 2 of the drawing,a groove 21 is provided for the accommodation of a gasket 28 which abutsagainst the inner end of the ilexible diaphragm 26. In order to seal theouter end of the diaphragm, it is spun over so as ,to vtakesubstantially the same contour as the adjacent surface of the upper endof the expansion chamber I8. and may be attached thereto in any suitablemanner, such as by brazlng, as is indicated by the numeral 29. Thesealed construction is accomplished through a flexible diaphragm so thatrelative movement between the terminal cap and the expansion chamber I8will not aiect the sealed construction. In order to protect the flexiblediaphragm 24 it will be seen that the terminal cap 2| is provided with aflange or depending portion 30 which is spaced from the diaphragm by asuitable distance so as not to contact it but provides a cover therefor.

As will be seen more clearly in Fig. 3, the lower end of the conductoril is relatively rigidly attached to the inner end of the lower shellportion I2 through a metallic member 35. This member includes a tubularportion 38 which may be relativeLv rigidly attached to the adjacent endof the conductor Il in any suitable manner such as by providing s.threaded and sweated joint. In order to support the lower end of theconductor Il on the lower end of the shell and to absorb the reactiveforces which will be present in compressing the springs 2li, themetallic member 35 is provided with a shoulder portion 31 which abutsagainst an adjacent surface 38 of an inwardly extending collar portion39 at the lower end of the porcelain shell 2. If lt is desired to sealthis end, a gasket 4|| may be provided between the shoulder I1 and thesurface 38. The inner end of the metallic member 35 has threaded thereona' nut 4| which may abut against the inner surface 42 of the shoulderportion 39 of the porcelain shell. A gasket 43 may be provided betweenthe nu-t 4| and the surface 42 if desired.

'I'he above described construction may be assembled by threading andsweating conductor I5 with its insulation i6 into the metallic memberIt. After placing gasket 40, lower porcelain I2 and gasket 43 inposition the joint seal may be obtained by tightening nut 4|. Afterbolting in position supporting flange I3 the top porcelain may be placedin position. The top chamber Il which has been preassembled with washer25, springs 2l and flexible diaphragm 26 can next be placed intoposition. With gasket 28 in position the terminal cap 2| may be screwedinto place and due to the cooperation of the threads sion of the springsby mere visual inspection it will be seen that the flange portion lllterminates relatively close to an adjacent portion 5|! of the expansionchamber Il. The amount of clearance, therefore, between the adjacentportions will give a visual indication of the amount of compression ofthe springs 2li for any particular temperature conditions as long asthere has been obtained a previous calibration of spring compression inrelation to the clearances between the depending flange portion 30 andthe adjacent portion 50 of the expansion chamber.

If it is desired to obtain further protection of the flexible diaphragmthan that which will obtain by the covering thereof due to the dependingflange, the clearance portion may be filled with a flexible gasketmember 5| as will be seen in Fig. 4.

Although we have shown and described particular embodiments of ourinvention, we do not desire to be limited to the particular embodi mentsdescribed, and we intend in the appended claims to cover allmodifications which do not depart from the spirit and scope of ourinvention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. In a bushing for electrical apparatus, a shell of insulating materialhaving an end portion, a conductor within said shell` cap means forenclosing said end portion, means for adjustably attaching said end capto said conductor, resilient means between said end cap and said endportion, said adjustable attaching means providing relative axialadjustment between said end cap and said conductor and for adjusting thecompression of said resilient means, flexible diaphragm means betweensaid end cap and said shell end portion, means providing a substantiallyfluid-tight connection between said diaphragm and said cap and betweensaid diaphragm and said shell end portion, said cap means having aflange portion substantially enclosing said diaphragm and terminatingrelatively close to said shell end portion. the amount of clearancebetween said end cap and said shell end portion giving a visualindication of the relative amount of compression of said resilientmeans.

2. In a bushing for electrical apparatus, a, shell of insulatingmaterial having a metallic end portion, a conductor within said shell,end cap means, means for adjustably attaching said end cap means to saidconductor, spring means, means including end cap means and said springmeans for resiliently attaching said conductor to said shell endportion, means for relatively rigidly attaching said conductor to theopposite end of said shell, means including a flexible diaphragm forproviding a substantially fiuidtight seal between said shell end portionand said conductor, adjustment between said end cap and said conductoradjusting the compression of said resilient means, said end cap meanssubstantially enclosing said diaphragm means and having a portion spacedfrom said metallic end portion to provide a relatively small clearance,the amount of clearance giving a. visual indication of the relativecompression of said resilient means.

3. In a. bushing for electrical apparatus, a shell of insulatingmaterial having a metallic expansion chamber on one end, a conductorwithin said shell, end cap means adjustably connected to said conductor,resilient means for supporting said end cap and conductor on saidchamber, means for relatively rigidly attaching said conductor to theopposite end of said shell, axial adjustment of said cap means and saidconductor determining the relative compression of said spring means,means including flexible diaphragm means providing a substantiallyiluid-tight seal .between said cap and said chamber, said cap meanssubstantially enclosing said diaphragm means and having aportiomadjacent said chamber, the amount of clearance between saidchamber and said cap giving a gage of the relative amount of compressionof said resilient means. l

4. In a bushing for electrical apparatus, a shell of insulating materialhaving a metallic expansion chamber on one end, a conductor within saidshell. end cap means adjustably connected to said conductor, resilientmeans for supporting said end cap andsconductor on said chamber, meansfor relatively rigidly attaching said conductor to the opposite end ofsaid shell, axial adjustment of said cap means and said conductordetermining the relative compression of said resilient means, meansincluding flexible diaphragm means providing a substantially fluid-tightseal between said cap and said chamber, said cap means substantiallyenclosing said diaphragm means and having a portion adjacent saidchamber, the amount of clearance between said chamber and said capgiving a gage of the relative amount of compression and resilient means,and ilexible gasket means between the adjacent portions of said cap andsaid chamber for protecting said flexible diaphragm.

5. In a bushing for electrical apparatus, a shell of insulating materialhaving an end portion, a conductor within said shell, end cap means forsubstantially enclosing said end portion, means for adjustably attachingsaid end cap means to said conductor, resilient means between said endcap means and said end portionl said adjustably attaching meansproviding relative axial adjustment between said end cap means and saidconductor and for adjusting the compression of said resilient means,means providing a substantially Huid-tight seal between the end capmeans and said shell end portio said end cap means having a flangeportion substantially enclosing said seal means and terminatingrelatively close to said shell end portion, the amount of clearancebetween said end cap means and said shell end portion giving a visualindication of the relative amount of compression of said resilientmeans.

STEPHEN TERPAK. LYNN WE'I'HERIIL.

